In February 1906, readers of Cosmopolitan magazine opened its pages to this statement: “Treason is a strong word, but not too strong to characterize the situation in which the Senate is the eager, resourceful, and indefatigable agent of interests as hostile to the American people as any invading army could be.” This indictment launched a nine-part series of articles entitled “Treason of the Senate.”

The “Treason” series placed the Senate at the center of a major drive by Progressive Era reformers to weaken the influence of large corporations and other major financial interests on government policy making. Direct popular election of senators fit perfectly with their campaign to bring government closer to the people.

As originally adopted, the Constitution provided for the election of senators by individual state legislatures. In the years following the Civil War, that system became increasingly subject to bribery, fraud, and deadlock. As Congress took on a greater role in shaping an industrializing nation, those with a major business stake in that development believed they could best exert their influence on the U.S. Senate by offering financial incentives to the state legislators who selected its members.

The campaign for direct election of senators took on new force in 1906, following conviction of two senators on corruption charges. Each had taken fees for interceding with federal agencies on behalf of business clients. The resulting negative publicity inspired publisher William Randolph Hearst, then a U.S. House member and owner of Cosmopolitan magazine, to commission popular novelist David Graham Phillips to prepare a series of investigative articles.

Making the point that large corporations and corrupt state legislators played too large a role in selection of senators, these articles doubled Cosmopolitan’s circulation within two months. Yet, Phillips' obvious reliance on innuendo and exaggeration soon earned him the scorn of other reformers. President Theodore Roosevelt saw in these charges a politically motivated effort by Hearst to discredit his administration, and coined the term "muckraker" to describe the Phillips brand of overstated and sensationalist journalism.

For several decades before publication of Phillips’ series, certain southern senators had blocked the direct election amendment out of fear that it would increase the influence of African-American voters. By 1906, however, many southern states had enacted “Jim Crow” laws to undermine that influence. The Phillips series finally broke Senate resistance and opened the way for the amendment’s ratification in 1913.